Method for the production of ball tip writing instruments



vIVIEIITfli-M, 5 7 H. R.'FEHLlNG ETAL- 2,879,586

METHOD FOR THE PRODUCTION OF BALL TIP WRITING INSTRUMENTS Filed Oct. 6,1952 v United States Patent METHOD FOR THE PRODUCTION OF BALL TIPWRITING INSTRUMENTS Hans Reinhard Fehling, London, and Ernest ArthurWicks,

Maple Durham, Reading, England, assiguors to Compania Uruguaya deFomento Industrial S.A., Montevideo, Uruguay This invention concernsreservoir writing instruments of the ball tip type wherein the writingextremity or nib comprises a writing ball rotatably housed in and partlyprotruding from a socket or housing, which ball is supplied with inkfrom a reservoir by means of a feed duct or a passage of capillary sizewhich communicates with the base of the socket or housing so that, asthe ball is rotated by being moved over and in contact with a surfacesuch for example as that of a sheet of paper, a thin film of ink iscarried by the ball through the narrow gap between it and its housingand is deposited as a trace on the said surface; specifically theinvention relates to writing extremities of such instruments.

Heretofore it has been customary to machine writing extremities for suchinstruments from solid bar stock, and to form such extremities in themanner described in British patent specification 609,817 H. G. Martin,or 564,172 L. J. Biro, U. S. Patent No. 2,390,636. The object of thepresent invention is a simplified form of writing extremity and a simplemethod of manufacturing same.

The invention therefore provides a method for the production of awriting extremity for a ball tip writing instrument of the typespecified from a tube having an internal diameter substantially equal tothe diameter of the ball, which comprises the steps of forming aconstriction in the bore of the tube and thereby producing a socket baseor stop for preventing movement of the writing ball down the tube, anddeforming the end of the tube to retain the ball in the socket.

Preferably, the deformation is elfected by constricting an end of thetube to provide a lip for retaining the ball in the socket; specificallythe internal constriction in the tube is formed by pressure appliedexternally to the said tube.

It is preferred that the constriction in the bore shall consist of aplurality of (and preferably three) inward protrusions, for this resultsin the production of a plurality of bore seat portions separated byaxially-extending ink channels.

Preferably, but not necessarily, a part-spherical base seat is formedsimultaneously with the act of constriction by inserting into thetubular material a member having a part-spherical end surface andapplying the external pressure in such manner that the localconstriction is moulded partly around said part-spherical end surface.

The invention further includes in or for a ball tip writing instrumentof the type specified, a writing extremity of tubular form with the ballsocket at one end between an inturned lip on the tube and a localconstriction in the bore of the tube produced by inward deformation ofthe material of the tube Walls. The inward deformation, or the maximuminward deformation is preferably presented at a plurality ofcircumferentially spaced locations producing spaced base seat portionsseparated by axially extending ink channels.

The foregoing and other features of the invention are incorporated inthe writing extremity andin the method of manufacture which will now bedescribed in detail with reference to the accompanying drawings in whichFigure l is a sectional elevation through the ball socket part of awriting extremity according to this invention;

Figure 2 is a plan view thereof with the ball removed;

Figure 3 is a sectional elevation illustrating the tool employed ineffecting the constriction and in producing part-spherical base seatsfor the ball,

Figure 4 illustrates a method of forming the lower part of the lateralseat surrounding the ball;

Figures 5 and 6 illustrate a further method of forming the lateral andthe base seat.

Referring to Figures 1 and 2 the writing extremity 1 is made from metaltube having a bore 2 slightly larger than the diameter of the writingball 3, which latter is conveniently 1 mm. in diameter. If the tube ismade of an aluminium alloy sold under the registered trademark Duraluminit may have a wall thickness of approximately 0.25 mm. It may beproduced by any manufacturing process known in the manufacture-oftubular material; for example, it may be extruded, or cold drawn.

The exterior of the tube is indented at 4 at a plurality of locationswhich are preferably equally spaced apart about the circumference. Aconvenient and desirable number for such indentations is three.

The indentations are, of course, efiected by externally applied pressureand they result in the bore of the tube being constricted by an equalnumber of inward prot1usio-ns 5 which as shown are separated by axiallyextending ink channels 6. These inward protrusions constitute a baseseat for the ball 3 and they are preferably but not necessarily providedwith part-spherical base seating surfaces 7 of the same radius as theball. The ball is held in position by the inward constriction of the lip8 of the tube 1. This inward constriction is eifected by spinning orswaging and preferably the end of the tube is chamfered as at 9 toassist in producing constriction.

The constricted lip 8 is disposed above the equator of the ball (suchequator being indicated by the chain dotted line 10) and is preferablyso produced that the inner surface of the constricted lip also assumes apart-spherical configuration constituting a part-spherical lateral seat11. As shown in Figure 1 this lateral seat 11 is disposed wholly orsubstantially wholly above the equator 10, but the constriction of thelip 8 may be so carried out that the lateral seat extends also below theequator of the ball.

It will further be appreciated that owing to the fact that the writingextremity is manufactured from a tube having a cylindrical bore ofsubstantially the same diameter as the ball 3 the wall of the ballsocket extending between the lateral seating and the inwardprotrusionsis of cylindrical formation as indicated at 12. Therefore there is alsoproduced a ball-encircling cavity 13 with which the channels 6 connect.

The constriction of the lip 8 may be so carried out that the gap betweenthe ball and its socket or housing is not less than .001 mm. and notmore than .01 mm. when this gap is measured in the manner described inBritish patent specification No. 629,283 H. G. Martin, the writingextremity being then well adapted for use with an oleaginous ink theviscosity of which is not less than 15 poise at 37 C.

Figure 3 illustrates a tool which is employed in the manufacture of thewriting extremity. It consists of a body 14 having a bore 15 of a sizeto permit the insertion and removal of the tube 1 but afiording acomparatively close fit for said tube. This bore is of a predetermineddepth terminating in a shoulder 16 and co-axially therewith there is asmaller bore 17 of substantially the same diameter as the bore of thetube, on which is fixed a male member 18 having a part spherical-end 19protruding to a predetermined extent into the bore 2. At appropriatelocations around the circumference of the tool there are radiallyslidable indenting punches 20-. In. the drawing the punch at the lefthand side is shown in the inner position and that at the right hand sideshown in. the outer position. The ends of these punches areappropriately shaped to produce the indentations 4, and the plane inwhich, their axes lie is spaced a predetermined distance from theshoulder 16. Although the punches are shown as, having conical ends,they may with advantage be substantially square-ended so that the inwardprotrusions are formed by what is, to some extent, a shearing of themetal of the tube walls.

In operation the tube 1 with its end chamfered as at 9 in Figure 1 isinserted in to the bore 15 until it is pressed against the shoulder 16.The member 18 being fixed in position in the tool, the part-sphericalend 19 of said member is thus entered into the bore of the tube. Thepunches 20 are then forced inwards to a predetermined extent which mayfor example be limited by enlarged heads 21. Thus the indentations 4 areformed, and owing to the disposition of the plane of the axes of saidpunches with regard to the part-spherical end 19 the inward protrusions5 are moulded partly about said end 19 thereby producing thepart-spherical base seat surfaces 7.

The punches 20 may be forced in by mechanical means such for example asa ring'cam, or hydraulically or pneumatically or in any other suitablemanner. They are likewise retracted in any suitable manner.

After the retraction of the punches the tube 1 is extracted, a ball,which may be the writing ball or a similar ball is dropped into the endof the tube so as to rest on the surface 7' and then the lip of the tubeis constricted by spinning or swaging. At any stage during theseoperations the tube may be cleaned of dirt and swarf by a jet ofcompressed air.

In the modified method of forming the lower lateral seat, Fig. 4 (i.e.that part of the lateral seat which is below the ball equator) there isused tubing 1 having a bore of slightly less diameter than the hall. Forexample, if the writing ball is 1 mm. diameter, the tube bore may be0.90 mm. diameter. The member 18 being about the same diameter as theball, when the hemispherical end 19 is entered into the tube said member18 acts as a punch and the bore of the upper end of the latter isenlarged to 1 mm. and is caused to conform to the said end 19 so that apart-spherical lower lateral seat 21 is produced.

In the modified method illustrated in Figs. 5 and 6, the tool 14 is voidof the member 18, so that neither the base seat 7, nor the lower lateralseat below the equator of the ball 3, are formed while this tool is inuse but are formed during a subsequent swagingprocess. After removal ofthe indented tube from the tool 14, a ball 3 is inserted in the end ofthe tube (Fig. 5) and then, by use of a swaging die 22 as shown in Fig.6 the end of the tube is constricted about the ball to produce the upperand lower lateral seat and the ball is pressed onto the protrusion 5' toform base seatings in them. To obtain the correct protrusion of the ballafter swaging, the included angle in the interior of the swaging tool 22should be about 80 and-the included angle to which, the end of thetubeis chamfered (as at 9) before swaging should be about 62".

In the manufacture of the writing extremity there may be employed eithera conventional automatic in which various tools are mounted on a turretor the like and are indexed so as to be presented one after another tothe work piece, or a specially constructed machine in which successivetools are disposed at spaced locations around a circle and a workcarrier carrying a plurality ofwork pieces is indexed so as to presenteach work piece to each of the tools in turn.

If a conventional automatic is employed the sequence of operations is asfollows (a length of-v the tubing being inserted in the machine headstock):

(1) The tube is fed out to a stop on the turret.

(2) The end of the tube is faced and tapered.

(3) The head stock is brought to a standstill, the tube entered into thetool described and the latter is operated as already described to formthe inward protruberances (and if desired the base seat, or base seatand lower lateral seat).

(4) The ball is inserted.

(5) The head stock is restarted and the ball is fixed in position byspinning or swaging.

(6) The length of tube appropriate for the writing extremity is partedoff from the tubular stock.

If the specially constructed machine is employed the tubular stock maybe cut to appropriate lengths on a separate machine or as an additionaloperation on the special machine and the sequence of operations inrespect of each writing extremity is as follows:

(1) A cut length or blank is fed into a loading collet on a turn table(there being a plurality of such collets at spaced locations around theturn table).

(2) The end of the blank is chamfered.

(3) The constrictions and inward protruberances (and if desired the baseseat, or the base seat and the lower lateral seat) are formed by thetool already described.

(4) The ball is inserted.

(5) The ball is secured by spinning or swaging.

(6) The finished writing extremity is ejected by compressed air.

What we claim is:

l. A method for the production of a writing extremity for a ball tipwriting instrument of the type specified, from tubing, which comprisesthe steps of forming a local constriction in the bore of the tube at oneend thereof by externally-applied indenting pressure thereby producing abase in the bore constriction for a ball socket, forming apart-spherical base seat for the ball simultaneously with the act ofconstriction by inserting into the tube a member having a part-sphericalend surface and applying the external pressure whereby the localconstriction is moulded partly around said part-spherical end suracewhereby said base seat is formed, inserting a ball member in the base,and constricting an end of the tube to provide a lip retaining the ballin the socket upon said base seat.

2. A method of making a writing extremity for a ball point pen of thetype specified, consisting in inserting a hollow tube of boresubstantially equal to the diameter of the writing ball in a female die,inserting into the end of the bore, through the die, a tool having apart-spherical end face, forming a plurality of inwardly extendingprotrusions in the tube by applying pressure to at least three pointsspaced around theperiphery of the tube and extending through holesformed in the die, said protrusions eon tacting said part-spherical endface and being molded thereby, removing the tube. and inserting a ball,and applying a tool to the end of the tube, with the ball in position toswage the end of the tube in the formation of a ball-retaining lip.

3. A method for the production of a writing extremity for a ball tipwriting instrument which comprises taking a tube of uniform innerdiameter, introducing abutment means in the tube, applying indentingpressure at circumferentially spaced points on the exterior part of thetube adjacent the abutment means whereby the inner periphery of thetube, at points corresponding to said circumferentially spaced points,is caused to protrude in molded contact with said abutment means to forma base seat for the ball, inserting a ball member in said tube on saidbase seat, and constricting an end of the tube to provide a retaininglip for theball.

(References on following page) 5 References Cited in the file of thispatent UNITED STATES PATENTS Thomas Sept. 7, 1886 Eisler Dec. 16, 1941Schrader et a1. Feb. 21, 1950 Segal Mar. 14, 1950 Knobel July 28, 1953Cloutier Sept. 20, 1955 Belgium June 30, 1952

